5.2 Igneous Rocks

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Vocabulary

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extrusive rock-rock that hardens on the earths surface
intrusive rock-rock that hardens below the earths surface
porphyritic texture-a rock with large crystals scattered in a bakground of much smaller crystals

Outline

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Igneous rocks

• Characteristics of Igneous rock
• Origin
  • Geologists classify rocks by where they were formed
• Texture
  • The texture of a igneous rock can vary depending on the size and shape of mineral crystals
    • the size of crystal depend on how the rock cooled
• Mineral Composition
  • The silica content of magma and lava affects how easily magma or lava will flow
• Uses of Igneous Rocks
  • Ignoeus rocks has been widly used for tools and building materials